﻿#region Legal

// Jimmy Zimmerman
// Team Mongoose
//
// END USER LICENSE AGREEMENT
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// OTHER RIGHTS AND LIMITATONS
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#endregion

using System;
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Linq;

namespace DiceRoller.Dice
{
    /// <summary>
    /// Repsents the composite of multiple <see cref="Die"/> instances rolled together.
    /// </summary>
    public class Dice : Die
    {
        #region Fields

        private readonly IEnumerable<Die> dice;

        #endregion

        #region Constructor
        
        /// <summary>
        /// Initializes a new instance of the <see cref="Dice"/> class with the supplied <see cref="Die"/> instances to roll together.
        /// </summary>
        /// <param name="dice">A params array of <see cref="Die"/> instances to be rolled together.</param>
        public Dice(params Die[] dice) : base(Int32.MaxValue)
        {
            Contract.Requires<ArgumentNullException>(dice != null, "dice");
            Contract.Requires<ArgumentException>(Contract.ForAll(dice, die => die != null), "dice");
            Contract.Requires<ArgumentException>(dice.Count() > 0, "dice");

            this.dice = dice.ToArray();
        }

        #endregion

        #region Overrides

        /// <summary>
        /// Gets the summation of the minimum value of all consituent die instances in the <see cref="Dice"/> composite.
        /// </summary>
        /// <remarks>This operation will performed overflow checked summation.</remarks>
        /// <value>The minimum value the dice can select when rolled.</value>
        /// <exception cref="OverflowException">The total value of all composed <see cref="Die"/> instances exceeded <see cref="Int32.MaxValue"/>.</exception>
        public override Int32 MinimumValue
        {
            get
            {
                checked
                {
                    var summation = this.dice.Sum(die => die.MinimumValue);
                    return summation;
                }
            }
        }

        /// <summary>
        /// Gets the summation of the maximum value of all consituent die instances in the <see cref="Dice"/> composite.
        /// </summary>
        /// <remarks>This operation will performed overflow checked summation.</remarks>
        /// <value>The maximum value the dice can select when rolled.</value>
        /// <exception cref="OverflowException">The total value of all composed <see cref="Die"/> instances exceeded <see cref="Int32.MaxValue"/>.</exception>
        public override Int32 MaximumValue
        {
           get
           {
               checked
               {
                   var summation = this.dice.Sum(die => die.MaximumValue);
                   return summation;
               }
           }
        }

        /// <summary>
        /// Rolls and accumulates each constituent <see cref="Die"/> instance in the <see cref="Dice"/> composite, returning the summation of all rolls.
        /// </summary>
        /// <remarks>This operation will performed overflow checked summation.</remarks>
        /// <returns>The summation result of the random roll for all composed elements.</returns>
        /// <exception cref="OverflowException">The total value of all rolls exceeded <see cref="Int32.MaxValue"/>.</exception>
        public override Int32 Roll()
        {
            var rolls = dice.Select(die => (Func<Int32>) die.Roll);

            checked
            {
                var summation = rolls.Sum(roll => roll());
                return summation;
            }
        }

        #endregion
    }
}
